XF 1.5 Another catigory inside a forum?

This title I had no idea how to word, I only have pictures! I want my 'Apply For Staff' catigory to have another catiogry displayed above the other: https://gyazo.com/dc083cac501fb3acedbbb0b07198f05e I know this is super confusing and if you have any questions that may help solve this forum feel free to comment below!